Dual mode optical navigation device

ABSTRACT

There is provided a dual mode optical navigation device. The dual mode optical navigation device is configured to operate in a first mode or a second mode on a working surface. The dual mode optical navigation device includes an image sensor and a processor. The image sensor captures an image frame of the working surface. The processor calculates a ratio of a bright area and a dark area in one image frame capture by the image sensor, enters the first mode in response to the calculated ratio being larger than a ratio threshold, and enters the second mode in response to the calculated ratio being within a ratio threshold range. The ratio threshold range is smaller than the ratio threshold.

RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 16/237,786, filed on Jan. 2, 2019, which is acontinuation application of U.S. application Ser. No. 15/919,698, filedon Mar. 13, 2018, which is a continuation application of U.S.application Ser. No. 15/596,595, filed on May 16, 2017, which is acontinuation application of U.S. application Ser. No. 14/165,831, filedon Jan. 28, 2014, the disclosures of which are hereby incorporated byreference herein in their entirety.

BACKGROUND

1. Field of the Disclosure

This disclosure generally relates to an optical navigation device and,more particularly, to a dual mode optical navigation device that mayswitch the operation mode according to different operating states.

2. Description of the Related Art

The conventional optical navigation device, such as an optical mouse,generally includes a light source, an image sensor and a process unit.When a user operates the optical mouse on a working surface, the lightsource illuminates the working surface and the image sensor receiveslight reflected from the working surface. The process unit of theoptical mouse calculates a movement value corresponding to the user'soperation according to the images successively captured by the imagesensor and converts the movement value to an electric signal. A hostthen relatively controls a cursor movement according to the electricsignal.

With the popularity of gesture operations, users can perform gestureoperations via a touch interface such as a touch pad or a touch screen,for example in Microsoft Windows 8, Google Android and Apple iOS.Compared with the touch interface, conventional optical mice only havelimited applications due to only being able to relatively control cursormovements according to the movement value.

For increasing functions (or operating modes) of the optical mouse, aroller is generally added to the optical mouse to be operated by theuser, e.g. rolling the roller to implement window scrolling or zoomingin/out, or a plurality of buttons for performing relative functions areadded. However, using such additional elements to improve the userexperience, the optical mouse can have problems of low accuracy, poordurability (e.g. due to abrasion of the roller) and large volume (e.g.due to ergonomic design of the pressing area of the buttons).

Accordingly, the present disclosure further provides a dual mode opticalnavigation device and a mode switching method thereof that have a cursorcontrol mode and a gesture operation mode simultaneously.

SUMMARY

The present disclosure provides a dual mode optical navigation devicethat may replace the function of the roller in conventional opticalnavigation devices so as to increase the practicality.

The present disclosure further provides a dual mode optical navigationdevice that may perform gesture operations according to a displacementof the navigation device relative to a working surface so as to enhancethe user experience.

The present disclosure provides a dual mode optical navigation deviceconfigured to operate in a first mode or a second mode on a workingsurface. The dual mode optical navigation device includes an imagesensor and a processor. The image sensor is configured to capture animage frame of the working surface. The processor is configured tocalculate a ratio of a bright area and a dark area in one image framecaptured by the image sensor, enter the first mode in response to thecalculated ratio being larger than a ratio threshold, and enter thesecond mode in response to the calculated ratio being within a ratiothreshold range. The ratio threshold range is smaller than the ratiothreshold.

The present disclosure further provides a dual mode optical navigationdevice configured to operate in a first mode or a second mode on aworking surface. The dual mode optical navigation device includes animage sensor and a processor. The image sensor is configured to capturean image frame of the working surface. The processor is configured tocalculate a first average brightness of a fully bright image frame, andenter the first mode in response to the first average brightness beinglarger than a brightness threshold, and calculate a second averagebrightness of a bright area and a dark area contained in one capturedimage frame, and enter the second mode in response to the secondbrightness within a brightness threshold range.

The present disclosure further provides an optical navigation deviceconfigured to operate on a working surface to control a cursor movementor perform a gesture operation. The optical navigation device includesan image sensor and a processor. The image sensor is configured tocapture an image frame of the working surface. The processor isconfigured to calculate a ratio of a bright area and a dark area in oneimage frame captured by the image sensor, control the cursor movement inresponse to the calculated ratio being larger than or equal to a ratiothreshold, perform the gesture operation in response to the calculatedratio being within a ratio threshold range, wherein the ratio thresholdrange is smaller than the ratio threshold, and neither control thecursor movement nor perform the gesture operation in response to thecalculated ratio being between the ratio threshold and the ratiothreshold range.

In one embodiment, the first mode is configured to control a cursormovement according to image frames captured by the image sensor; and thesecond mode is configured to perform a gesture operation according toimage frames captured by the image sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the present disclosurewill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

FIG. 1 shows a schematic diagram of the dual mode optical navigationdevice operating in the first mode according to the first embodiment ofthe present disclosure.

FIG. 2 shows a schematic diagram of the dual mode optical navigationdevice operating in the second mode according to the first embodiment ofthe present disclosure.

FIG. 3a shows a relationship between the operating angle and the imagequality of the dual mode optical navigation device according to thefirst embodiment of the present disclosure.

FIG. 3b shows a schematic diagram of image frames captured by the imagesensor of the dual mode optical navigation device according to theembodiment of the present disclosure.

FIG. 4 shows a schematic diagram of the dual mode optical navigationdevice operating in the first mode according to the second embodiment ofthe present disclosure.

FIG. 5 shows a schematic diagram of the dual mode optical navigationdevice operating in the second mode according to the second embodimentof the present disclosure.

FIG. 6 shows a flow chart of the mode switching method of the dual modeoptical navigation system according to the embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT

It should be noted that, wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

Referring to FIG. 1 and FIG. 2, FIG. 1 shows a schematic diagram of adual mode optical navigation device 1 operating in a first modeaccording to the first embodiment of the present disclosure and FIG. 2shows a schematic diagram of the dual mode optical navigation device 1operating in a second mode according to the first embodiment of thepresent disclosure. The dual mode optical navigation device 1 includes afirst bottom surface 11, a second bottom surface 12, a light source 14,an image sensor 16 and a process unit 18. The image sensor 16 iselectrically connected to the process unit 18. A user (not shown) mayoperate the dual mode optical navigation device 1 on a working surface Sin a first mode or a second mode with his/her palm or a plurality offingers, wherein the first bottom surface 11 of the dual mode opticalnavigation device 1 is configured to be contacted with the workingsurface S in the first mode and the second bottom surface 12 of the dualmode optical navigation device 1 is configured to be contacted with theworking surface S in the second mode.

The dual mode optical navigation device 1 may be an optical mouse deviceand connected to a mobile device, a smart TV, a computer system or thelike through wire/wireless protocols such as PS/2, USB, Bluetooth orWi-Fi so as to perform corresponding actions accordingly, e.g.controlling a cursor movement when the dual mode optical navigationdevice 1 operates in the first mode and performing a gesture operationwhen the dual mode optical navigation device 1 operates in the secondmode, or vice versa. It is appreciated that controlling a cursormovement herein may be referred to controlling a cursor movement on adisplay device; and performing a gesture operation herein may includewindow scrolling, object zooming and volume control. In addition, thedual mode navigation device 1 of the present disclosure may furthercooperate with an application program to extend the gesture operationthereof.

In addition, those skilled in the art are appreciated that the dual modeoptical navigation device 1 may further have a housing for the user toput the palm or finger(s) thereon so as to perform operations, and thehousing is also configured to protect the above mentioned elements. Itis appreciated that the first bottom surface 11 and the second bottomsurface 12 are a part of the bottom surface of the housing respectively,as shown in FIG. 1.

The dual mode optical navigation device 1 may be operated by contactingthe working surface S with the first bottom surface 11 in useroperation. In the present embodiment, a contact area of the first bottomsurface 11 is preferably larger than a contact area of the second bottomsurface 12 so that the dual mode optical navigation device 1 may presetthe first bottom surface 11, but not limited to, to contact with theworking surface S.

There is an included angle θ between the second bottom surface 12 andthe first bottom surface 11, wherein the second bottom surface 12 islocated at a back end of the first bottom surface 11 under the dual modeoptical navigation device 1, as shown in FIG. 1, but the presentdisclosure is not limited thereto. In other embodiments, the secondbottom surface 12 of the dual mode optical navigation device 1 may belocated at a left end or a right end of the first bottom surface 11under the dual mode optical navigation device 1. For conforming toergonomic design, the included angle θ is preferably within 150-180degrees.

It should be mentioned that in the present disclosure the dual modeoptical navigation device 1 is described with only one second bottomsurface (i.e. the second bottom surface 12). In other embodiments, thedual mode optical navigation device 1 may have a plurality of secondbottom surfaces 12 located at at least one of a back end, a left end ora right end of the first bottom surface 11 under the dual mode opticalnavigation device 1. For example, the dual mode optical navigationdevice 1 may have two second bottom surfaces 12 respectively located ata left end and a right end of the first bottom surface 11 under the dualmode optical navigation device 1 so that the dual mode opticalnavigation device 1 may be adapted to both left-handed users andright-handed users.

In addition, the dual mode optical navigation device 1 may be operatedby contacting the working surface S with the second bottom surface 12 inuser operation. Since the first bottom surface 11 and the second bottomsurface 12 have the included angle θ therebetween, the first bottomsurface 11 and the second bottom surface 12 of the dual mode opticalnavigation device 1 do not contact with the working surface S at thesame time. When the first bottom surface 11 contacts the working surfaceS, there forms a maximum operating angle θ_(M) (i.e. a complementaryangle of the included angle θ) between the second bottom surface 12 andthe working surface S. Similarly, there forms the maximum operatingangle θ_(M) between the first bottom surface 11 and the working surfaceS when the second bottom surface 12 contacts the working surface S. Thatis to say, the dual mode optical navigation device 1 has an operatingangle between the angles of θ-θ_(M).

The light source 14 may illuminate the working surface S through anopening or a light transmissive medium (not shown) at the first bottomsurface 11, wherein the light source 14 may be a light emitting diode(LED), a laser diode (LD) or other active light sources. The spectrum ofthe light source 14 is preferably adapted to a spectrum range that theimage sensor 16 can receive. Furthermore, a light guide element may bedisposed on the optical path between the light source 14 and the imagesensor 16 so that the image sensor 16 can receive reflective light fieldof the light source 14 effectively.

The image sensor 16 is configured to capture image frames of the workingsurface S through the opening or the light transmissive medium of thefirst bottom surface 11, wherein the image sensor may be a complementarymetal oxide semiconductor (CMOS) image sensor or charge-coupled device(CCD) image sensor, but not limited thereto. Furthermore, to preventexternal light sources from disturbing the image sensor 16 in capturingthe image frame, the image sensor 16 may be covered with a film coatingconfigured to filter out spectrums rather than the spectrum of the lightsource 14.

In an embodiment, the image sensor 16 may be embedded in the processunit 18. In another embodiment, the image sensor 16 may be integratedwith the light source 14 as an optical unit.

It should be mentioned that no matter which of the first bottom surface11 or the second bottom surface 12 of the dual mode optical navigationdevice 1 contacts with the working surface S, the light source 14 has toilluminate the working surface S to provide reflective light needed bythe image sensor 16 while capturing image frames. Therefore, the spatialrelationship between the light source 14, the image sensor 16, the firstbottom surface 11 and the second bottom surface 12 is arranged in a wayso that the image sensor 16 can receive reflected light from the workingsurface S in both the first and second modes.

The process unit 18 is configured to calculate an image feature of theimage frame and accordingly enter the first mode or the second mode. Theprocess unit 18 may be a digital signal processor (DSP) or other processdevices that can be used to process image data according to the imageframe captured by the image sensor 16. The process unit 18 is notlimited to software or hardware. Preferably, the process unit 18 maycontrol the light source 14 to turn on and off.

It should be mentioned that the image feature of the present embodimentmay be an image quality. As shown in FIG. 3a , it shows a relationshipbetween the operating angle and the image quality of the dual modeoptical navigation device 1, wherein when the first bottom surface 11 ofthe dual mode optical navigation device 1 contacts with the workingsurface S (e.g. the state of FIG. 1), the image quality calculated bythe process unit 18 is larger than (or equal to) a quality thresholdvalue (e.g. Q1 of FIG. 3a ) and the dual mode optical navigation device1 enters the first mode. And, when the user applies an external force P1onto the dual mode optical navigation device 1 to allow the secondbottom surface 12 to contact with the working surface S (e.g. the stateof FIG. 2), the image quality is within a quality threshold range (e.g.a range from Q2 to Q3 of FIG. 3a ) and the dual mode optical navigationdevice 1 enters the second mode. The image quality may be referred tocommonly owned U.S. Pat. Nos. 7,142,695, 7,444,006 and 7,116,801.

The quality threshold and the quality threshold range may be previouslysaved in a memory unit before the dual mode optical navigation device 1leaves the factory. It is appreciated that reflective light fieldreceived by the image sensor 16 becomes weaker when the dual modeoptical navigation device 1 switches from the first mode to the secondmode, and thus the quality threshold range is preferably smaller thanthe quality threshold. For example, Q1 shown in FIG. 3a may be definedas the quality threshold, and the range from Q2 to Q3 may be defined asthe quality threshold range; wherein the quality threshold Q1 and thequality threshold range Q2-Q3 may be set according to actual measurementresults. In the present embodiment, the range from Q1 to Q2 may beserved as a buffer when the dual mode optical navigation device 1switches from the first mode to the second mode or from the second modeto the first mode so as to prevent misoperations. For example, when theprocess unit 18 identifies that the image quality of the image frame iswithin the quality threshold range Q1-Q2, it means that the dual modeoptical navigation device 1 is operated neither in the first mode nor inthe second mode, and the process unit 18 may not post-process the imageframe.

In addition to the above mentioned image quality, in another embodimentthe image feature may be an intensity distribution ratio. For example,referring to FIG. 3b , when the first bottom surface 11 of the dual modeoptical navigation device 1 contacts with the working surface S (e.g.the state of FIG. 1), an image frame F1 captured by the image sensor 16is fully bright, and thus the process unit 18 may determine that theintensity distribution ratio of the image frame F1 is larger than orequal to a ratio threshold so as to enter the first mode. When an imageframe F2 captured by the image sensor 16 has a bright area and a darkarea, the process unit 18 may determine whether the intensitydistribution ratio formed by the bright area and the dark area (e.g.bright area/dark area) is within a ratio threshold range to enter thesecond mode, wherein the ratio threshold range may be smaller than theratio threshold.

In another embodiment, the image feature may be an image brightnessvalue. Referring to FIG. 3b , the process unit 18 may calculate theimage brightness value respectively according to two image frames F1 andF2 captured by the image sensor 16, e.g. calculating an averagebrightness value of two dimensional pixels of the image frame F1 and anaverage brightness value of two dimensional pixels of the image frame F2and then comparing the average brightness values with a brightnessthreshold respectively. Similarly, the process unit 18 may determinewhether the image brightness value is larger than or equal to abrightness threshold or within a brightness threshold range so as toenter the first mode or the second mode.

Therefore, in the present disclosure the image feature may include anintensity distribution ratio, an image brightness value or an imagequality. Besides, the process unit 18 may further calculate an imageprofile of the image frame, identify a boundary location in the imageframe or process the image frame with other methods to obtain the imagefeature.

On the other hand, the process unit 18 further calculates a displacementaccording to image frames of the working surface S successively capturedby the image sensor 16. In the present embodiment, the method of theprocess unit 18 calculating the displacement is well known, e.g.calculating the displacement according to correlations between imageframes, and thus details thereof are not described herein.

In the present embodiment, the first mode of the dual mode opticalnavigation device 1 is configured to control a cursor movement, and thesecond mode is configured to perform a gesture operation.

Referring to FIG. 4 and FIG. 5, FIG. 4 shows a schematic diagram of adual mode optical navigation device 2 operating in a first modeaccording to the second embodiment of the present disclosure and FIG. 5shows a schematic diagram of the dual mode optical navigation device 2operating in a second mode according to the second embodiment of thepresent disclosure. The dual mode optical navigation device 2 includes afirst bottom surface 21, a second bottom surface 22, a light source 24,an image sensor 26, an actuator 27 and a process unit 28. The imagesensor 26 and the actuator 27 are electrically connected to the processunit 28 respectively. The dual mode optical navigation device 2 may beoperated in a first mode or a second mode on a working surface S,wherein the first mode is configured to control a cursor movementaccording to a displacement and the second mode is configured to performa gesture operation according to the displacement.

Similar to the first embodiment of the present disclosure, there is anincluded angle θ between the second bottom surface 22 and the firstbottom surface 21, and the first bottom surface 21 is configured to becontacted with the working surface S in the first mode and the secondbottom surface 22 is configured to be contacted with the working surfaceS in the second mode. The light source 24 is configured to illuminatethe working surface S through the first bottom surface 21. The imagesensor 26 is configured to capture image frames of the working surface Sthought the first bottom surface 21 for the process unit 28 calculatinga displacement, wherein the image sensor 26 captures image frames of theworking surface S through the first bottom surface 21 in both the firstand second modes.

The difference between the present embodiment and the first embodimentis that the dual mode optical navigation device 2 further has theactuator 27, and the actuator 27 is configured to generate a detectsignal Sd when one of the first bottom surface 21 and the second bottomsurface 22 in contact with the working surface S changes from the firstbottom surface 21 to the second bottom surface 22 or from the secondbottom surface 22 to the first bottom surface 21. The process unit 28may determine whether the dual mode optical navigation device 2 entersthe first mode or the second mode according to the detect signal Sd.

Referring to FIG. 4 and FIG. 5, for example when the actuator 27 is amechanical switch, the actuator 27 of the present embodiment may bedisposed at the second bottom surface 22. When the user applies anexternal force P2 onto the dual mode optical navigation device 2 toallow the second bottom surface 22 to contact with the working surfaceS, the actuator 27 is pressed and generates a pressed signal. Then theprocess unit 28 determines that the dual mode optical navigation device2 enters the second mode according to the pressed signal.

Similarly, when the user releases the external force P2, the dual modeoptical navigation device 2 goes back from the state of FIG. 5 to thestate of FIG. 4. Meanwhile the actuator 27 recovers and generates arecovery signal, and the process unit 28 determines that the dual modeoptical navigation device 2 enters the first mode according to therecovery signal. In the present embodiment, both the pressed signal andthe recovery signal are belong to the detect signal Sd.

It should be mentioned that the present embodiment exemplarily showsthat the second bottom surface 22 is located at a back end of the firstbottom surface 21 under the dual mode optical navigation device 2, andthe actuator 27 is disposed at the second bottom surface 22, but thepresent invention is not limited to. In another embodiment, the dualmode optical navigation device 2 may have two second bottom surfaces 22respectively located at a left end and a right end of the first bottomsurface 21 under the dual mode optical navigation device 2, and theactuator 27 is disposed at the second bottom surface(s) or at the firstbottom surface only. Thus the number and location of the actuator 27 ofthe dual mode optical navigation device 2 may be determined according toactual applications; that is to say, the actuator 27 may be disposed atthe first bottom surface 21, the second bottom surface 22 or otherlocations of the dual mode optical navigation device 2.

On the other hand, the actuator 27 of the present embodiment isexemplarily shown as a physical button, but not limited thereto. Theactuator 27 may be a capacitive switch, an optical switch or otherswitch elements that may be configured to detect the switching betweenthe first bottom surface 21 and the second bottom surface 22 andgenerate a detect signal correspondingly.

In other embodiments, the actuator 27 may be a gyroscope or anaccelerometer. For example, disposing a gyroscope or an accelerometer inthe dual mode optical navigation device 2, when one of the first bottomsurface 21 and the second bottom surface 22 in contact with the workingsurface S changes from the first bottom surface 21 to the second bottomsurface 22 or from the second bottom surface 22 to the first bottomsurface 21, the gyroscope or the accelerometer may generate a detectsignal Sd for the process unit 28 determining the mode of the dual modeoptical navigation device 2. The actuator 27 may be integrated with theprocess unit 28 as a control chip when the actuator 27 is a gyroscope oran accelerometer.

Similarly, parameters associated with the actuator 27 may be previouslyset before the dual mode optical navigation device 2 leaves the factory.For example, momentum parameters associated with one of the first bottomsurface 21 and the second bottom surface 22 in contact with the workingsurface S changing from the first bottom surface 21 to the second bottomsurface 22 or from the second bottom surface 22 to the first bottomsurface 21 are respectively previously saved in a memory unit.Therefore, the process unit 28 may switch the dual mode opticalnavigation device 2 to the first mode when the first bottom surface 21contacts with the working surface S and switch the dual mode opticalnavigation device 2 to the second mode when the second bottom surface 22contacts with the working surface S according to the detect signaloutputted by the actuator 27.

As mentioned above, the conventional optical navigation device onlyrelatively controls cursor movements according to a displacement andhave problems of low accuracy, poor durability and large volume.Therefore, the present disclosure further provides a dual mode opticalnavigation device and a mode switching method thereof that may have acursor control mode and a gesture operation mode simultaneously, and maydetermine whether a first bottom surface or a second bottom surfacecontacts with a working surface according to an image feature of animage frame associated with the working surface (FIGS. 1, 2 and thefirst embodiment) or according to a detect signal of a gyroscope, anaccelerometer or a switch element (FIGS. 4, 5 and the second embodiment)thereby switching the mode of the dual mode optical navigation device tocontrol a cursor movement or perform a gesture operation. Accordingly,the problems existing in the conventional optical navigation device maybe overcome.

Although the disclosure has been explained in relation to its preferredembodiment, it is not used to limit the disclosure. It is to beunderstood that many other possible modifications and variations can bemade by those skilled in the art without departing from the spirit andscope of the disclosure as hereinafter claimed.

What is claimed is:
 1. A dual mode optical navigation device, configuredto operate in a first mode or a second mode on a working surface, thedual mode optical navigation device comprising: an image sensorconfigured to capture an image frame of the working surface; and aprocessor configured to calculate a ratio of a bright area and a darkarea in one image frame captured by the image sensor, enter the firstmode in response to the calculated ratio of the bright area and the darkarea being larger than a ratio threshold, and enter the second mode inresponse to the calculated ratio of the bright area and the dark areabeing within a ratio threshold range, wherein the ratio threshold rangeis smaller than the ratio threshold.
 2. The dual mode optical navigationdevice as claimed in claim 1, wherein the first mode is a mode forcontrolling a cursor movement.
 3. The dual mode optical navigationdevice as claimed in claim 1, wherein the second mode is a mode forperforming a gesture operation.
 4. The dual mode optical navigationdevice as claimed in claim 1, further comprising: a light sourceconfigured to illuminate the working surface, wherein the image sensorcomprises a film coating configured to filter out spectrums other than aspectrum of the light source.
 5. The dual mode optical navigation deviceas claimed in claim 1, wherein in response to the calculated ratio ofthe bright area and the dark area being between the ratio threshold andthe ratio threshold range, the processor is configured to notpost-process the image frame.
 6. The dual mode optical navigation deviceas claimed in claim 1, further comprising a gyroscope configured togenerate a detection signal for confirming the first mode and the secondmode.
 7. A dual mode optical navigation device, configured to operate ina first mode or a second mode on a working surface, the dual modeoptical navigation device comprising: an image sensor configured tocapture an image frame of the working surface; and a processorconfigured to calculate a first average brightness of a fully brightimage frame, and enter the first mode in response to the first averagebrightness being larger than a brightness threshold, and calculate asecond average brightness of a bright area and a dark area contained inone captured image frame, and enter the second mode in response to thesecond average brightness of the bright area and the dark area within abrightness threshold range.
 8. The dual mode optical navigation deviceas claimed in claim 7, wherein the first mode is a mode for controllinga cursor movement.
 9. The dual mode optical navigation device as claimedin claim 7, wherein the second mode is a mode for performing a gestureoperation.
 10. The dual mode optical navigation device as claimed inclaim 7, further comprising: a light source configured to illuminate theworking surface, wherein the image sensor comprises a film coatingconfigured to filter out spectrums other than a spectrum of the lightsource.
 11. The dual mode optical navigation device as claimed in claim7, further comprising a gyroscope configured to generate a detectionsignal for confirming the first mode and the second mode.
 12. An opticalnavigation device, configured to operate on a working surface to controla cursor movement on a display device or perform a gesture operation,the optical navigation device comprising: an image sensor configured tocapture image frames of the working surface; and a processor configuredto calculate a ratio of a bright area and a dark area in one image framecaptured by the image sensor, control the cursor movement in response tothe calculated ratio of the bright area and the dark area being largerthan or equal to a ratio threshold, perform the gesture operation inresponse to the calculated ratio of the bright area and the dark areabeing within a ratio threshold range, wherein the ratio threshold rangeis smaller than the ratio threshold, and neither control the cursormovement nor perform the gesture operation in response to the calculatedratio of the bright area and the dark area being between the ratiothreshold and the ratio threshold range.
 13. The optical navigationdevice as claimed in claim 12, wherein the gesture operation compriseswindow scrolling, object zooming and volume control.
 14. The opticalnavigation device as claimed in claim 12, wherein the processor isconfigured to calculate displacement according to the image frames ofthe working surface successively captured by the image sensor, andcontrol the cursor movement or perform the gesture operation accordingto the calculated displacement.